To supply additional data for a more complete knowledge of the action of aldosterone on the renal tubule and to examine a possible mechanism of aldosterone escape, the effect of aldosterone administration on renal kallikrein concentration and on kinin levels will be examined. Aldosterone will be continuously infused into intact, conscious dogs and kallikrein and kinin concentrations will be analyzed daily along with changes in urinary electrolyte and fluid excretion. In addition, the marked increase in adrenal sensitivity after sodium depletion to any of the known aldosterone-stimulating agents will be examined in an attempt to determine the mechanism of the increased sensitivity. Studies will be continued to determine what pituitary factor is necessary for aldosterone stimulation during sodium depletion. BIBLIOGRAPHIC REFERENCES: MaCaa, R.E., J.M. Montalvo and C.S. McCaa. Role of the Pituitary in the Regulation of Aldosterone Secretion. (Rapid Communication) Internat. Res. Comm. Syst. 4:124, 1976. McCaa, R.E., C.R. Roberts and C.S. McCaa. Role of the Renin-Angiotensin System in the Regulation of Aldosterone Biosynthesis During Sodium Deprivation in Intact Conscious Dogs. (Rapid Communication) Internat. Res. Comm. Syst. 4:126, 1976.